Heart failure (HF) is a major and increasing clinical problem that is associated with substantial morbidity and mortality. It is the leading cause of admission to hospital in individuals older than 65 years.
As the population lives longer resulting in an increased prevalence of cardiovascular risk factors and diseases, and as survival following acute myocardial infarction (Ml) increases, the number of patients living with congestive heart failure (CHF) is expanding. For example, risk factors such as hypertension are common prognostic comorbidities in chronic HF. In parallel, a concomitant increase in the number of hospitalizations for acute decompensated heart failure (ADHF) has occurred. In the United States alone, heart failure (HF) affects 5.7 million Americans, with over 650,000 new cases diagnosed annually, with increasing hospitalization rates.
Heart failure remains a high unmet medical need with an annual mortality rate of about 20%. Reductions in mortality and cardiovascular morbidity have been achieved by the renin-angiotensin-aldosterone system (RAAS) blockers (Angiotensin Converting Enzyme (ACE) inhibitors and Angiotensin Receptor Blockers (ARBs)) and beta (3)-blockers in HF. While survival rates have improved for HF with reduced ejection fraction (HF-REF) over recent decades, due to more widespread use of drugs that block RAAS and improved acute care, residual mortality rates remain high. For patients with HF with preserved ejection fraction (HF-PEF) no therapy has proven to be effective at reducing morbidity and mortality. Overall, the therapeutic benefits of RAAS blockade with ACE inhibitors and/or ARBs remain limited, possibly caused by angiotensin II escape due to incomplete ACE inhibition or angiotensin II originating from alternative non-ACE pathways, and by other neuro-hormonal and other mechanisms contributing to cardiac disease and outcomes.
A supramolecular complex comprising valsartan, which is an ARB, and AHU-377 (Sacubitril), which is a neprilysin inhibitor, has been approved by US Food and Drug Administration (FDA) under the brand name Entresto for the treatment of heart failure with reduced ejection fraction.
Valsartan blocks the angiotensin II receptor type 1 (AT1). This receptor is found on both vascular smooth muscle cells and the zona glomerulosa cells of the adrenal gland which are responsible for aldosterone secretion. In the absence of AT1 blockade, angiotensin causes both direct vasoconstriction and adrenal aldosterone secretion, the aldosterone then acting on the distal tubular cells of the kidney to promote sodium reabsorption which expands extracellular fluid (ECF) volume. Blockade of (AT1) thus causes vasodilation and reduction of ECF volume.
AHU-377 is a prodrug that is activated to sacubitrilat (LBQ657) by de-ethylation via esterases. AHU-377 inhibits the enzyme neprilysin, a neutral endopeptidase that degrades vasoactive peptides, including natriuretic peptides, bradykinin, and adrenomedullin. Thus, AHU-377 increases the levels of these peptides, causing vasodilation and reduction of ECF volume via sodium excretion.
Entresto is a first-in-class medicine (an Angiotensin Receptor Neprilysin Inhibitor, or ARNI) and has a unique mode of action which is thought to reduce the strain on the failing heart. It harnesses the body's natural defenses against heart failure, simultaneously acting to enhance the levels of natriuretic and other endogenous vasoactive peptides, while also inhibiting the renin-angiotensin-aldosterone system (RAAS).
Furthermore, crystallinity of drugs effects, among other physical and mechanical properties, their solubility, dissolution rate, hardness, compressability and melting point. Because these properties may, in turn, effect a drug's manufacture and their utility, there is an existing need in the chemical and therapeutic arts for identification of crystalline forms of drugs and ways of reproducibly making them.
Though one crystalline form of the supramolecular complex comprising valsartan and AHU-377 has been reported to exist as a trisodium hemipentahydrate form in U.S. Pat. No. 8,877,938 B2 (the “patent form”), new crystalline forms of the supramolecular complex comprising valsartan and AHU-377, in particular stable polymorphs with superior pharmacological activities suitable for formulation, and convenient methods to prepare them remain a great need.